<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button id="btn">click me</button>

    <script>
        //DOM2事件可以设置多个事件，缺点是写起来麻烦
        var btn = document.getElementById('btn')
        btn.addEventListener('click',function(){
            alert('同意你碰我')
        })

        btn.addEventListener('click',function(){
            alert('同意撤回了')
        })

    </script>
</body>
</html>